The invention concerns a catalyst component for an alpha olefine-polymerizing catalyst, which comprises an organoaluminum compound, an electron donor, and a solid catalyst component which is obtained when a compound containing magnesium has reacted with a titanium halide compound. The present invention is also directed to a procedure for manufacturing this catalyst component, and to a procedure for polymerizing the alpha olefines, especially propylene, which makes use of the catalyst component.
Catalysts which have been manufactured according to the prior art with high activity for polymerizing alpha olefines include an aluminum alkyl compound, an electron donor, and a halogenated titanium compound on a carrier substance comprising various magnesium compounds. Chlorinated magnesium compounds have generally been used as the magnesium compound, which may be, for instance, water-free magnesium chloride alone or together with other magnesium compounds, or an organic magnesium compound which has been prepared by halogenating organic magnesium compounds with the aid of chlorine-containing compounds.
In polymerizing catalysts of this type, the properties of the solid carrier component have significant influence upon the properties of the ultimate catalyst, e.g. upon its activity. These properties can be substantially influenced through the mode of manufacturing of the carrier component.
The present invention concerns a catalyst component in which the carrier component has been prepared from magnesium sulfate or from minerals containing the same. The minerals may be natural minerals or synthetic minerals. The use of various magnesium salts for carriers for magnesium chloride treated with titanium halides for preparing inert carrier components for Ziegler-Natta catalysts for the purpose of polymerizing olefines is not norel per se. However, it has turned out to be difficult to manufacture active Ziegler-Natta catalysts exclusively from magnesium sulfate and from minerals containing the same, in particular those catalysts for the polymerizing of propylene, because in these processes the catalysts are highly sensitive to moisture and to the crystallized water contained in the carrier. Even minimal quantities of crystallized water already significantly reduce the activity of the catalyst. Magnesium sulfate and minerals containing magnesium sulfate generally contain considerable quantities of crystal water and are therefore unsuitable for use in propylene-polymerizing catalysts.